San Francisco
— Digital Equipment Corporation first decided to undertake a worker-health study in 1984, after several employees at the company's chip-manufacturing plant in Hudson, Mass., mentioned experiencing miscarriages. The findings, released in December, startled industry representatives. Women workers in one section of the plant's ``clean room'' (so named because even dust particles are filtered out of the air during chip production) reported having miscarriages at double the rate of the national average. The study, however, did not attempt to single out a cause.

Since then, some scientists who have reviewed the study have expressed concern about its accuracy. For example, none of the miscarriages reported by employees were medically confirmed, notes Ellen Silbergeld, a toxicologist with the Environmental Defense Fund.

Part of the problem is that little is known about the health effects of chemicals, gases, and other substances used in the semiconductor industry, says Joseph LaDou, a professor of medicine at the University of California at San Francisco who has studied health-related issues in the semiconductor industry for several years.